Returning once more to the particular case in question, it is obvious that our new knowledge points to the desirability of keeping the seed beds and nurseries especially clean from groundsel and weeds of that description: on the one hand, such weeds are noxious in themselves, and on the other they harbor the _Coleosporium_ form of the fungus _Peridermium_ under the best conditions for infection. It may be added that it is known that the fungus can go on being reproduced by the _uredospores_ on the groundsel plants which live through the winter. * * * * * In St. Genevieve and Cape Girardeau Counties, Mo., in the Niagara limestone is found a handsome marble of a variegated liver color. Near Sheppard Landing it is 80 feet thick, and at Janis Mill, in St. Genevieve County, Dr. Shumard speaks of beds of fine texture and various shades of flesh, yellow, green, pink, purple, and chocolate, all handsomely blended. * * * * * A NEW CATALOGUE OF VALUABLE PAPERS Contained in Scientific American Supplement during the past ten years, sent _free of charge_ to any address. MUNN & CO., 361 Broadway, New York. * * * * * THE SCIENTIFIC AMERICAN ARCHITECTS AND BUILDERS EDITION. $2.50 A YEAR. SINGLE COPIES, 25 CTS. This is a Special Edition of the Scientific American, issued monthly--on the first day of the month. Each number contains about forty large quarto pages, equal to about two hundred ordinary book pages, forming, practically, a large and splendid MAGAZINE OF ARCHITECTURE, richly adorned with _elegant plates in colors_ and with fine engravings, illustrating the most interesting examples of modern Architectural Construction and allied subjects. A special feature is the presentation in each number of a variety of the latest and best plans for private residences, city and country, including those of very moderate cost as well as the more expensive. Drawings in perspective and in color are given, together with full Plans, Specifications, Costs, Bills of Estimate, and Sheets of Details. No other building paper contains so many plans, details, and specifications regularly presented as the Scientific American. Hundreds of dwellings have already been erected on the various plans we have issued during the past year, and many others are in process of construction. Architects, Builders, and Owners will find this work valuable in furnishing fresh and useful suggestions. All who contemplate building or improving homes, or erecting structures of any kind, have before them in this work an almost _endless series of the latest and best examples_ from which to make selections, thus saving time and money.